Siemens, the German-based industrial technology giant, is this weekend leading a last-ditch rallying cry to save the CBI, the ailing business lobbying group.

Sky News has learnt that Siemens, which employs 11,000 people in Britain, is coordinating a letter among a group of CBI members to urge them to publicly endorse its survival.

The letter, which is to be sent to a national newspaper later on Sunday and which has been seen by Sky News, is understood to have been signed by Microsoft.

A small number of companies ranging in size from start-ups to giant corporate names have been asked to put their names to it, sources said on Sunday.

It has been written two days before a vote of CBI members will determine the Royal Charter-bearing organisation’s future as it grapples with a sexual misconduct scandal which has cut it adrift from government.

The Siemens-coordinated letter acknowledges its signatories’ revulsion at the allegations which have rocked the CBI, saying “it is clear the culture of the organisation fell far below expectations”.

This is at odds with the CBI’s own conclusion outlined in a prospectus published ahead of Tuesday’s extraordinary general meeting.

The draft letter goes on to say: “At a time when the UK economy is facing strong economic headwinds and anaemia growth, and with a general election expected before the end of next year, it is vital that there is a credible voice representing all sectors and sizes of UK business.

“The CBI can do this. The next 18 months will be vital for the UK and as a group, we feel it is essential that a refocused, effective CBI re-establishes its ties with government and provides the voice that British business needs.”

Ministers and the Labour Party have refused to engage with the CBI while a police investigation into rape allegations is ongoing, a period which could last many months.

Jeremy Hunt, the chancellor, has said there is “no point” interacting with it after it was deserted in droves by leading corporate members such as Aviva and the John Lewis Partnership.

Public shows of corporate support have been conspicuously absent since the CBI was plunged into crisis.

However, in their joint letter, Siemens, Microsoft and their fellow signatories say they “believe that the CBI has recognised its failings and has a robust action plan in place to be delivered by a new leadership”.

Since the scandal engulfed the CBI in March, it has ousted its director-general, Tony Danker, and said it would accelerate a search for a new president.

“Of critical importance to us is that the CBI recognises that the necessary change will take a significant, ongoing and concerted effort to repair their culture and rebuild confidence,” the letter says.

“We see encouraging signs that this is recognised, the learnings as to what went wrong and why are being understood, and that a new culture is beginning to become embedded in the organisation.

“This is why we’re backing the CBI to change and move forward, and this group will vote to give the organisation a mandate to continue.

“This is not a blank cheque and we will hold the CBI to account in delivering on its action plans.”

A number of other members have expressed dissatisfaction with the CBI’s reform document, saying it had left them underwhelmed and that it had no financial or strategic plan for the CBI’s future.

To illustrate the apathy felt by many corporate members, PricewaterhouseCoopers, the UK’s biggest accountancy firm, does not plan to register a vote in next week’s ballot, according to insiders.

Sky News revealed last week that the board of the CBI had drafted in lawyers to prepare for a prospective insolvency filing ahead of the crunch vote.

An adverse outcome from a vote at next week’s extraordinary general meeting would leave directors with little choice but to begin a process to wind it up.

Next week’s EGM will take place on a ‘one member, one vote’ basis, with the CBI requiring a majority of votes cast in favour of a resolution expressing confidence in its ability to continue.

“Without a mandate from you, we have no future,” Rain Newton-Smith, the new director-general, has told members.

Siemens and Microsoft declined to comment, while the CBI has been contacted for comment.